Connection between rotating shafts, for example, in a case that a rotating shaft of a product under test such as an engine is connected to a rotating shaft of a testing device such as a dynamometer, is implemented as shown in FIG. 15, as follows. A spline shaft 104 is attached to a rotating shaft of a product under test 103 such as an engine which is mounted on a pedestal 101 through a rubber mount member 102. On the other hand, a spline shaft 107, with which the spline shaft 104 is fitted through a universal joint 106 and others, is attached to a rotating shaft (shaft to be connected) 105 of a testing device (not shown) such as a dynamometer. The spline shaft 107 is supported by a shaft support member 108.
The rotating shaft of the product under test is connected to the rotating shaft of the testing device by moving the shaft support member 108 by a shaft support member drive mechanism 109 such as an air cylinder toward the product under test 103, and thereby causing the spline shaft 104 to fit in spline shaft 107. If there is a deviation in axis between spline shaft 107 and spline shaft 104, the deviation is absorbed by the universal joint 106 and others (see patent documents 1-3, for example).